Differential adjustment for condition responsive devices



Nov. 29, 1949 2,489,422

C. W. KUHN DIFFERENTIAL ADJUSTMENT FOR CONDITION RESPONSIVE DE ES Filed Jan. 2, 47

Patented Nov. 29, 1949 DIFFERETIAL ADJUSTMENT FOR CONDI- TION RESPONSIVE DEVICES Clarence W. Kuhn, Wauwatosa, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application January 2, 1947, Serial No. 719,640

This invention relates'to condition responsive devices and more particularly to dierential adjustment thereof.

.In practice differential adjustment has been quite a problem, particularly in connection with sensitive devices, as for ek'ample the so-called j '10 Claims. (CL Z4-522) microswitch, which as is well known is one usually of the snap type, biased to a given position, being operable to 'another' position by a relatively small force, and being restraina'ole against its bias by a force less than that required to move it against its bias.

An object of the invention is to provide a differential adjustment for condition responsive devices, including those of the character just mentioned, which may be readily and inexpensively provided for and which will afford adjustment of differential without disturbing the range adjustment or other essential adjustments.

Another object is to provide such a diierential adjustment which will enable the diierential to be reduced to a very small value and which may be varied in a simple and convenient manner.

Another object is to provide for differential adjustment through the medium of means attording positive drive of the actuating' element of the controlled switch or other device by the condition responsive means, as distinguished from drive through a resilient part.

Another object is to provide for differential adjustment through the medium of rugged and durable means.

Other objects and advantages-oi the invention will hereinafter appear.

One embodiment of the invention is illustrated in the accompanying drawing, it being understood that the embodiment illustrated is susceptible of various modications without departing from the scope of the appended claims.

In the drawing Fig. 1 is an elevational view of a condition re" sponsive switch embodying the invention;

Fig. 2 is a top plan view of Fig. 1;

Fig. 3 is a more or less schematic view of means embodied in the device of Figs. 1 and 2;

Figs. 4, 5 and 6 are perspective views of certain elements shown in Fig. 1; `and Fig. 'l is a more or less schematic View depict- 1 ing the method of assembling the parts shown in Figs. 5 and 6.

Referring to Figsfl and 2, they show a device comprising an enclosed switch l to -be assumed t0 be of the aforementioned "microswitc type, said switch being controllable by condition responsive element 2 which will be assumed tobe spring 6.

:a pressure responsive element, although it might frame 4 carried by a right angle plate 5 to which "the pressure responsive element 2 is suitably attached. This particular assembly while advantageous is not essential and hence will not bef described in detail. The inverted U-shaped frame 4 has mounted therein a loading spring 6 for the pressure responsive element 2, which ele v ment may be assumed to be of the diaphragm type and said loading spring has an adjusting, screw l accessible at the top of frame 4. As will be understood, the adjustable loading spring pro-LA vides for range adjustment but not for dinerential adjustment.

Switch I has a reciprocable actuating element y I0 projecting beyond the enclosure of said switch and directly engaged by a lever I I which may be. formed of rigid material and which has no op-1v erative connection with the pressure responsive element except through a. lever I2, said levers having a free lost motion connection therebetween. Lever I2 is operatively connected to the unit comprising the pressure responsive element 1 2 and loading spring 6, and said lever has for engagement with lever II on opposite sides of the latter a button I3 and an adjustable screw I4, the head of which screw overhangs the end of lever II. Thus is provided a free lost motion connection between lever II and lever I 2; the degree of lost motion is variable by adjustment of screw I4. The lever II has means biasing it in a direction tending to press inwardly the switch actuating element I0, the force of suchv bias of lever II being variable by an adjusting L screw I5.

As more-clearly shown in Fig. 3. lever I2 is a .right angle lever and is mounted on a pivot pin 20 adjacent the junction of its perpendicularly disposed arms. The arm I2l projects between the pressure responsive element 2, here shown schematically as a diaphragm, and the loading Lever I2 preferably is of the form shown in Fig. 4, the arm I2n thereof being of channel form with bearings I2h in its side anges for the pivot pin 20, which pin may be and preferably is terminally supported by the inverted U-shaped frame 4 of Figs. 1 and 2. Lever I I prel-v erably is of the form shown in Fig. 5, having a short perpendicular arm I I'L reexed to provide a portion IIb to hook on to the pivot pin 2U between the side anges of arm I2*A of lever I2..

Levers II and I 2 thus have a common pivotal.

axis and lever II is biased in a counterclockwise direction by a leaf spring 2I carrying the aforementionad adjusting screw I5 to bear upon a xed abutment which as will be apparent from Figs. 1 and 2 is afforded by the right angle plate 5. Preferably the spring 2I is of the form shown in Fig. 6, having a transverse slot 2|a to accommodate a cross section of lever I I, an opening 2 Ib to receive a lug IIc on lever II, an opening 2Ic to aord clearance for the operating connection between the diaphragm 2 and lever I2a and a threaded opening 2ld to receive adjusting screw I5. Referring to Fig. '1 the slotted end of spring 2| may be slipped onto the lever II as shown in dotted lines and then along said lever to seat the extremity of the spring on the upper at surface of arm II and to afford the spring an opposed bearing against the free end of the hook IIb with lug I Ic extending into the opening 2lb of the spring as shown in full lines, thus to securely interlock said spring and lever.

yWith the construction shown and described adjustment of the spring bias of lever I Ibyadjustment of screw I5 enables the switch actuating element I to be so conditioned as to permit the switch normally to occupy an open or closed position to which it is inherently biased and yet to be movable to closed or open position, as the case may be, by a very slight movement of lever II by a force to be supplied by lever I2. As will be observed such adjustment of the bias of lever II is wholly independent of the range adjustment of the device and in fact wholly independent of the pressure responsive means including the loading spring 6. Such adjustment of the bias of lever II provides for the reduction in supplemental force required to cause movement of actuating element I 0 to actuate the switch. A preferred method of obtaining the desired adjustment is by turning the screw I to increase the bias of lever II to a degree sufficient to actuate the switch against its inherent bias and then to back oi the screw to reduce the bias to the desired degree. The desired degree of reduction of bias of lever II is that which renders the bias incapable of preponderating the inherent bias of the switch but rendering it suflicient to restrain the switch in the position to which it is moved against its inherent bias.

It has been found in practice that the desired degree of reduction of the bias of lever II may be obtained by backing olf screw I5 to such a position that the switch returns to its normal condition and then finally setting it at a point midway between the aforementioned two points of adjustment of the screw which provided for actuation and return of the switch. However, it will be apparent to those skilled in the art that the iinal position for screw I5 may be on either side of the mid-point.

Then to obtain the desired differential adjustment it is merely necessary to adjust the degree of free lost motion between the levers I I and I2. The pressure at which the lever I2 engages and supplements the force exerted by lever II counterclockwise is determined by the adjustment of loading spring 6 and the lower pressure at which lever I2 engages lever II to move it clockwise is determined by the adjustment of screw I4. As aforestated, when the lever l2 engages and operates lever II counterclockwise it effects operation of switch I to its open or closed position, as the case may be, in which position the switch is retained by the bias of lever II, when as the result of falling pressure the lever I2 begins to move clockwise. However, when lever I2 moves clockwise suilciently to engage the head of screw I4 with lever II it positively moves lever I I in a direction to permit switch I to resume its normal open or closed position under its own bias.

What I claim as new and desire to secure by Letters Patent is:

l. In condition responsive means to effect reverse operations of a controlled device biased to a given position, the combination with an element movable in opposite directions, and biasing means for said element adjusted for biasing it unidirectionally to subject the controlled device to a non-operating force sufcient to neutralize its bias, of means responsive to varying conditions and including an element movable in reverse directions selectively as a function of reversals of such varying conditions, and means providing a free lost motion connection between said elements fo'r positive operation by said second mentioned element of the rst mentioned element in reverse directions selectively after take-up of the lost motion, the last mentioned means including means to adjust the range of such lost motion, thereby to provide for adjustment of diierential Independently of adjustments of said means responsive to varying conditions.

2. For control of a device biased from a given position to another given position, the combination with a lever and adjustable biasing means therefor biasing it to subject the controlled device to a non-operating force such as to oppose and neutralize the bias of the latter when in the first mentioned given position, of means responsive to varying conditions and including a lever oscillating as a function of reversals of such varying conditions, and means providing a lost motion connection between said levers which connection subject to take-up of lost motion subjects the iirst mentioned lever to positive actuation by the second mentioned lever in reverse directions according to the direction of movement of the latter, the last mentioned means comprising means to adjust the range of such lost motion, thereby to provide for adjustment of differential independently of the adjustments of said means responsive to varying conditions.

3. Control means for a device-biased from a given position to another given position, comprising two levers, biasing means for one of said levers adjusted for biasing it to subject the controlled device to a non-operating force such as to oppose and neutralize the bias of the latter, and means providing a lost motion connection between said levers whereby subject to take-up of lost motion said biased lever is subject to positive actuation in reverse directions by the other of said levers according to the direction of movement of the latter, said means including means to adjust the range of Such lost motion.

4. Control means for a device biased from a given position to another given position, comprising two levers having a common fixed pivotal axis, biasing means for one of said'levers adjusted for biasing it to subject the controlled device to a non-operating force such as to oppose and neutralize the bias of the latter, and means providing a lost motion connection between said levers whereby subject to take-up of lost motion said biased lever is subject to positive actuation in reverse directions by the other of said levers according to the direction of movement of the latter, said means including means to adjust the range of such lost motion.

5. Control means for a device biased from a given position to another given position, comprising two levers having a common pivotal axis and being in a coplanar relation, one of said levers being an actuator for the other and said levers having relatively adjustable parts to provide a lost motion connection between said levers adjusty able in respect of range of lost motion, condition responsive means to oscillate said actuator lever and adjustable biasing means for said other lever subjecting the same to a bias opposed to the bias of said device and adjusted to be non-preponderating but suliicient to neutralize the bias of the controlled device, thereby to render said biased lever effective to restrain the controlled device during reverse take-up of lost motion between said levers after the controlled device has been moved out of the position to vwhich it is biased.

6. Control means for a device biased from a given position to another given position, comprising two levers having a common pivotal axis and being in a coplanar relation, one of said levers being an actuator for the other and said levers having relatively adjustable parts to provide a lost motion connection between said levers adjustable in respect of range of lost motion, condition responsive means to oscillate said actuator lever and biasing means for said other lever subjecting the same to a bias opposed to the bias of said device and adjustable to be non-preponderating but suicient to neutralize the bias of the controlled device, thereby to render said biased lever eective to restrain the controlled device during reverse take-up of lost motion between said levers aiter the controlled device has been moved out of the position to which it is biased, said biased lever having a hooked portion for its pivotal bearing and its said biasing means comprising a leaf spring apertured to be slipped onto said lever for coniinement of its extremity behind said hooked portion and for obtaining an opposed bearing against the free extremity of said hooked portion.

7. In combination, a device biased to a given position and comprising means which renders movement from such given position to a second position and vice versa dependent upon relative variations between its biasing force and an opposing force and which insures full movement of said device when leaving either position, a cooperating element movable in opposite directions, and having means constantly biasing it unidirectionally to subject said device to a non-operating force suicient to neutralize the bias of said device thus to restrain said device against return movement, means responsive to varying conditions including an element movable in reverse directions selectively as a function of reversals of such varying conditions, and means providing a lost motion connection between said elements which connection subject to take up of such lost motion subjects the first mentioned element to positive actuation in reverse directions according to the direction of movement of the second mentioned element, the last mentioned means including means to adjust the range of such lost m0- tion, thereby to provide for adjustment of differential independently of the adjustment of said means responsive to varying conditions.

8. In combination, a snap action device biased to a given position and requiring for operation to another given position application of a force greater than that required to restrain it against return movement, a cooperating element movable in opposite directions and having means constantly biasing it unidirectionally to subject said device to a non-operating force sufficient to neutralize the bias of said device to restrain said device against return movement, mean-s responsive to varying conditions including an element movable in reverse directions selectively as a function of reversals of such varying conditions, and means providing a lost motion Connection between said elements which connection subject to take-up of such lost motion subjects the first mentioned element to positive actuation in reverse directions according to the direction of movement or the second mentioned element, the last mentioned means including means to adjust the range of such lost motion, thereby to provide for adjustment of dii'erential independently of the adjustment of said means responsive to varying conditions.

9. In combination, a snap action device biased to a given position and requiring for operation to another given position application of a force greater than that required to restrain it against return movement, two levers, adjustable biasing means for one of said levers biasing it to subject the device to a non-operating force such as to oppose and neutralize the bias of said device to restrain said device against return movement and means providing a lost motion connection between said levers whereby subject to take up of lost motion said biased lever is subject to positive actuation in reverse directions by the other of said levers according to the direction of movement of the latter, said means including means to adjust the range of lost motion.

10. In combination, a snap action device biased to a given position and requiring for operation to another given position application of a force greater than that required to restrain it against return movement, two levers having a common xed pivotal axis and being in a coplanar relation, one of said levers being an actuator for the other and said levers having relatively adjustable parts to provide a lost motion connection between said levers adjustable in respect of range of lost motion, condition responsive means to oscillate said actuator lever and adjustable biasing means for said other lever subjecting the same to a bias opposed to the bias of said device and adjustable to be non-preponderating but suiiicient to neutralize the bias of the device, thereby to render said biased lever effective to restrain the device during reverse take-up of lost motion between said levers after the device has been moved out of the position to which it is biased, said biased lever having a hooked portion for its pivotal bearing and its said biasing means comprising a leaf spring apertured to be slipped onto said lever for connement of its extremity behind said hooked portion and for obtaining an opposed bearing against the free extremity of said hooked portion.

CLARENCE W. KUHN.

REFERENCES CITED The following references are of record in the file of thispatent:

UNITED STATES PATENTS Number Name Date 1,178,596 Okey Apr. 11, 1916 2,389,436 Kearney Nov. 20, 1945 

